The paper considers the issues of determining undissolved CaO and MgO particles in slags formed in a ladle-furnace unit. The assessment of slags by the presence and quantity of undissolved oxides CaO and MgO, depending on chemical composition, was carried out using a polymer model developed at UrFU and improved at IMeT UrB RAS. To determine the saturation of a multicomponent melt by CaO and MgO oxides, it is necessary to compare two parameters: thermodynamic activity of oxide in the melt, which depends on chemical composition, and saturation activity, which depends on temperature. The authors propose a method for estimating the content of undissolved particles in the slags formed at the steel ladle treatment at JSC VMZ. Most slags contain undissolved lime in an amount less than 10 %, which is sufficient for successful steel desulfurization. Theoretical calculations for determination of undissolved particles were confirmed in laboratory conditions during studies of industrial slags with a Stengelmeyer viscometer. Laboratory experiments showed the accuracy of the calculated method for determining the solid phase in the slags formed in ladle-furnace unit by comparing the viscosity changes with a decrease in the slags temperature. Solidification temperature of heterogeneous slag is 200 °C higher than that of homogeneous one. When temperature of heterogeneous slag decreased, enlarged agglomerates of solid oxides were formed, which fell under the measuring device, respectively, it showed an increased viscosity of the oxide system in the temperature range of 1570 – 590 °C. Laboratory experiments confirm the methodology for determining the solid phase in the slag.

In modern blast furnace production, even a short-term disruption of the technological process is associated with large productivity losses. In the practice of conducting blast furnace melting, there are often significant deviations from the optimal mode. They can lead not only to disruptions of the blast furnace, but also to accidents. In the operation of a blast furnace, typical deviations from the normal distribution of gas flow and charge materials include: peripheral, axial, channel passages; skewing of the backfill level; varying degrees and types of charge suspension. As a result, there are a cooling or excessive overheating of the furnace and violation of the melting operation. A serious consequence of the prolonged peripheral movement of gases is not only intensive wear of the lining, poor use of thermal and chemical energy of gases, but also stable cluttering of the hearth with formation of a deadman. Deadman is an ore-coke sinter formed in the tuyere zone of a blast furnace, as a result of cooling of its center. The paper describes the study and analysis of violations of blast furnace operation, analysis of the deadman causes and assessment of the accident rate of blast furnace tuyeres. Violation of gas distribution and hearth cluttering lead to formation of a deadman, which provokes mass burning of tuyeres and blast furnace refrigerators. The developed methodological foundations (mathematical model) allow us to estimate the maximum temperature of the tuyere zone and the resulting heat flow to the tuyere toe in presence of a deadman. It is shown that in large-volume blast furnaces, bubble outflow of the gas-coal flow prevails, contributing to growth of a deadman in the blast furnace.

The article is devoted to improving the wear resistance of forging tools, in particular punches for punching holes and cutting stamp dies. Low tool life leads to an increase in the cost of finished products, an increase in labor and material costs for replacing worn tools and adjusting them, a decrease in the productivity of pressing equipment and an increase in the number of defective products. A method is presented for theoretical research of solving the problem of calculating the temperature field of a stamp die tool during laser processing. A differential equation was compiled for a numerical solution of the problem. The authors proposed the modes of laser heat treatment of a punch for punching holes and a stamp die tool made of high-hardness steel. Field tests conducted in industrial conditions showed that the proposed laser heat treatment modes made it possible to increase resistance of the punch intended for punching holes by 2 – 3 times and the resistance of the stamp dies by 2.2 – 2.8 times.

Industrial slags produced by high-carbon ferrochrome are a material of complex composition consisting of an oxide part (Cr₂O₃, CaO, MgO, FeO, SiO₂, Al₂O₃) and “entangled” metal prills (Cr_met). In order to increase the degree of chromium utilization and reduce losses in the form of metal prills, we conducted the laboratory experiments to study changes in properties of the slag produced by high-carbon ferrochrome through the use of effective and affordable fluxing materials: expanded clay, calcium borate and refined ferrochrome slag. The effect of fluxing additives in the form of expanded clay, calcium borate and slag from the production of low-carbon ferrochrome on the properties of high-carbon ferrochrome slag was studied. Addition of up to 8 % of expanded clay and low-carbon ferrochrome slag leads to a stable decrease in the softening temperatures of the final slags. The greatest intensity of decrease in the softening temperature is observed when calcium borate is injected in an amount of 6 ‒ 10 %. The greatest effect on reducing softening temperatures is exerted by the addition of 10 % calcium borate when introducing high-carbon ferrochrome into the slag, while the temperature of softening beginning decreases by 262 °С, and the temperature of softening end – by 135 °С. All the studied fluxing additives have a positive effect on reduction degree of the residual concentration of metallic chromium in the slag. The most intense decrease in the content of Cr_met in the slag is observed with the introduction of 2 % of fluxing materials. The best values for the residual content of 0.7 ‒ 0.8 % Cr_met were achieved using 4 % of low-carbon ferrochrome slag and calcium borate. When using expanded clay, an additive in the amount of 10 % is required to achieve such indicators of Cr_met. In general, the effectiveness of using the studied fluxing materials to increase the degree of chromium extraction in the production of high-carbon ferrochrome is shown, its content in the slag is reduced by 84 %.

The paper studies fine structure of industrial steels with BCC lattice (pearlite, ferrite-pearlite and martensite) using transmission diffraction electron microscopy. The internal structure of the grains was analyzed; the scalar density of dislocations in various parts of the material, the sources of internal stresses and their amplitude were determined. The use of a method based on the analysis of bending extinction contours allowed us to study internal stresses. We analyzed the internal stresses and their sources using the example of 0.76С–Cr–V–Fe rail steel with a lamellar pearlite structure after ultra long-term operation with the tonnage of 1770 million gross tons. The metal of the rails was examined along the central axis of symmetry (rolling surface) and the rounding radius (working fillet) of the railhead at distances of 0, 2 and 10 mm from the surface. As one approaches the head surface, regardless of the research direction (along the fillet rounding radius or along the axis of symmetry), the lamellar pearlite is gradually replaced by destroyed pearlite with formation of a ferrite-carbide mixture and formation of a fragmented structure. These processes occur more intensively in the working fillet. Along the entire central axis of symmetry of the rail head (rolling surface), there is a plastic bending-torsion of the crystal lattice, along the rounding radius of the rail head (working fillet) at a distance of 10 mm from the surface – also plastic, and at a distance from 0 to 2 mm – elastic-plastic. The main source of internal torque (long-acting) stresses in rail steel is the excessive density of dislocations. Using the example of 34CrNi3MoVN steel of the martensitic class, the type of bending extinction contour was determined using mathematical equations. At low degrees of plastic deformation, extinction contours are contours of bending or torsion, at high degrees they are of a mixed type.

When choosing compositions of high-entropy alloys, one of the parameters taken into account is thermal stability. The paper considers the structural transformations of the deformed Al_0.3CoCrFeNi high-entropy alloy occurring during its annealing. The material was obtained by argon-arc melting with a mixture of pure single-element components. In order to homogenize the structure, the resulting ingot was subjected to thermomecha­nical processing according to a scheme combining cold rolling with a compression ratio of 50 % and low-temperature annealing (400 °C for 100 h). In the future, the homogenized billet was rolled in a cold state with a compression ratio of 80 %. The structure of the materials was studied directly during heating (in-situ mode) using the method of synchrotron X-ray diffraction. The heating rate of the samples was 20 °C/min, the maximum heating temperature was 1000 °C. The parameters of the alloy dislocation structure (density of screw dislocations, spatial distribution of dislocations) during heating were determined using the modified Williamson–Hall and Warren–Averbach methods. According to the data obtained, the temperature of beginning of formation of a high-entropy phase with a primitive cubic lattice is 560 °C. In the process of heating the material up to this temperature, an increase in density of screw dislocations and formation of a disordered dislocation structure are observed. The nature of change in dislocation density correlates well with the increase in the alloy microhardness. At an initial value of 406 ± 13 HV_0.1 (for the deformed material), the microhardness during heat treatment increases up to 587 ± 10 HV_0.1.

The authors studied the crystallization process of the Fe – W system, which is the basis of heat-resistant high-speed steel used in plasma arc surfacing on the surface of rolls and various cutting tools. The structure of this material consists of two components: cellular and dendritic. Histogram of the structural elements distribution shows the presence of a single maximum. The most probable size takes a value in the range of 10 – 15 μm. The paper considers the morphological instability of crystallization front (the Mullins-Sekerka instability). The model includes the equations of convective thermal conductivity and diffusion. The Stefan conditions for temperature were set at interface of the phases. Linear analysis of this instability is carried out for two cases: when the convective term in the equations of thermal conductivity and diffusion can be neglected; when convection prevails over diffusion processes. In all cases, it was assumed that the value (1 – k_s) was close to zero, which corresponds to a concentration of the alloying element approximately equal to or exceeding the eutectic one, and a short-wave approximation was also used. In the first case, the analytical view of dependence of the wavelength, which accounts for the maximum rate of interface disturbances growth, coincides with generally accepted concepts. In the second case, the value of this wavelength is directly proportional to square root of the interphase boundary velocity. The limits of applicability of these approximations for various mechanisms of crystal growth were determined. In the case of normal growth, both approximations provide an adequate explanation for the formation of structural elements up to 5 μm in size at a crystallization front velocity of about 2 m/s. For the case of growth due to screw dislocations, the wavelength value corresponding to the fastest-growing perturbation mode in the first case coincides with experimental data at a crystallization front velocity of the order of 10^–7 m/s, whereas in the convective approximation such a coincidence is observed at 10^–4 m/s. Further development of the model consists in simultaneous consideration of the convective and diffusion components. The results obtained will serve as a material for the research of the Mullins–Sekerka instability for two interface boundaries.

The paper studies the influence of heat treatment modes on the structure and properties of austenitic steel grade 08Kh18N6AG10S. Austeni­tic structure with twinned boundaries was preserved after quenching at 1040 and 1100 ℃. At the same time, the average size of austenitic grains decreased from 42.3 ± 6 μm (supply condition) to 38.1 ± 5.0 and 39.0 ± 4.5 μm, respectively. Quenching at 1040 ℃ leads to release of excess carbide phases at the grain boundaries. Mainly manganese and silicon oxides were found after quenching at 1100 ℃. Quenching at 1040 ℃ leads to a slight decrease in microhardness (by 12 %) compared to the condition of supply (from 3285 ± 80 to 2895 ± 70 MPa). The hardness decreases less after quenching at 1100 ℃ (up to 3090 ± 80 MPa). Quenching at 1040 and 1100 ℃ has significantly improved the fracture toughness of steel. Values of impact strength of the steel increased to 223 ± 10 and 240 ± 5 J/cm² compared to the condition of supply (55 J/cm²). The authors found that the steel samples demonstrate a comparable level of wear resistance during tests for abrasive wear compared to the condition of supply after quenching at 1040 and 1100 ℃. The mass loss after passing the roller distance of 4309 m for all steel conditions is approximately 8.0 %. The authors concluded that the most optimal heat treatment of 08Kh18N6AG10S steel is quenching at 1100 ℃, which improves the fracture toughness of steel while maintaining microhardness and wear resistance.

The authors studied the physical properties of the slags of CaO ‒ SiO₂ ‒ Al₂O₃ ‒ MgO system containing cerium oxide. The developed slags are based on a calcium silicate system, the basicity (CaO)/(SiO₂) of which has a great influence on the slag properties. Generalization of the performed studies results allowed obtaining new data on the effect of basicity in cerium-containing slags of the studied oxide system on viscosity, temperature of crystallization onset and structure. Experimental studies of the physical properties of cerium-containing slags showed that with an increase in basicity of 2.0 ‒ 5.0, an increase in temperature of crystallization onset and viscosity is observed associated with structure of the formed slags. An increase in basicity from 2.0 to 5.0 contributes to an increase in viscosity from 0.20 to 0.41 Pa·s at 1500 °C and an increase in the crystallization temperature from 1397 to 1497 °C. The structural analysis showed that the structure of the cerium-containing slag is influenced by both the Si⁴⁺ ion and the Al³⁺ ion, which are grid-forming agents. Silicon ions in this system are present in the form of [SiO₄]-tetrahedra, whereas aluminum ions are present in form of [AlO₄]-tetrahedra and [AlO₆]-octahedra. With an increase in basicity 2.0 to 2.5, the silicon structure becomes more complicated, and then at a basicity of 3.5 ‒ 5.0 it becomes simpler, whereas the aluminate one becomes more complicated due to an increase in the content of CaO, which participates in charge compensation of polymerized structural units [AlO₄]-tetrahedra with the formation of a more stable tetrahedral structure, and as a result of increased slag viscosity. Slags of the studied oxide system containing 15 % Ce₂O₃ are characterized by a sufficiently high liquid mobility in the considered basicity range.

The task of the present theoretical investigation was to determine the external factors at which a spherical shell mold will not fail due to temperature stresses occurring in it. The problem is formulated for determining the stress-strain state of the spherical shell mold formed in the support filler at cooling of solidifying spherical steel casting. The investigated axisymmetric rotational body has four zones: liquid metal, solid metal, shell mold, and support filler. To solve the problem, the equation of linear elasticity, the equation of heat capacity and a well-proven numerical method were used according to which the investigated zone is partitioned into elements by a system of orthogonal surfaces. For each element, a formulated system of equations is written in difference form, taking into account axial symmetry through the values ​​of stresses and displacements along the element edges and the lengths of the ribs’ arcs that limit its volume. The heat conduction equation is written in difference form for construction of a heat balance for an arbitrary orthogonal element, including both average temperature of the element and temperatures of the elements surrounding its volume. The authors found the solution of the difference analogue of heat equation by the “sweep” method according to the compiled iterative scheme. A diffe­rence analogue of the formulated system of differential equations of the linear theory of elasticity has the form of an algebraic system of equations. The algorithm for convolution of this system allows one to significantly reduce its rank. A general numerical scheme and algorithm for solving the problem are presented. The result of the solution is the magnitude of stresses, displacements on average along the edges of each element and average temperature in the element.

Duplex stainless steels are a modern class of materials with a unique combination of high corrosion and mechanical properties. Due to this, they can be widely used in machine parts and aggregates in fields with aggressive oil and gas production conditions. One of the disadvantages of these materials is their tendency to local corrosion damage on non-metallic inclusions, other things being equal, formed during smelting and casting. To control the purity of steel in conditions of open induction smelting, it is effective to use modification with rare earth metals (REM). Therefore, the purpose of this work was to determine the optimal content of REM in duplex steel to increase corrosion properties. Thermodynamic modeling of the formation of nonmetallic inclusions in duplex corrosion-resistant steel S32750 was carried out and the results of calculations were compared with the experimental data. It is shown that there is an optimal concentration of REM at which contamination with inclusions is minimal due to favorable conditions for their removal, and with a further increase in consumption it increases due to coagulation of a large number of refractory oxides. Electrochemical tests were performed and parameters such as corrosion potential, pitting formation potential and the basis of pitting resistance of experimental steels were determined. Therefore, the corrosion properties of the investigated duplex steel are significantly improved when treated with REM. The electro­chemical potentials of different types of inclusions are evaluated on a qualitative level. Based on the obtained results on corrosion resistance and contamination of the studied castings, the optimal amount of REM introduced for modifying inclusions is 0.05 % (0.65Ce + 0.35La).

The article is devoted to the study of dependence of carbon dioxide corrosion rate on the microstructure of material design of the pipeline for CO₂ transport and injection. Today there is a task of choosing such material design. For pipeline construction the most cost-effective materials are carbon steels, but for their application it is necessary to pay increased attention to the problem of carbon dioxide corrosion, which is intensified in wet, undrained CO₂ flows. At the same time, the choice of material should be made reasonably, taking into account the balance between corrosion resistance, mechanical characteristics and economic aspect of the issue. In this paper, the influence of microstructural state features on the corrosion rate of low-alloy mild steels for CO₂ transport and injection was investigated. The authors studied the features of steels with ferritic-bainitic, bainitic-ferritic-perlitic and ferritic-perlitic microstructures. Tests on corrosion resistance were carried out on the bench autoclave complex, which allows to recreate conditions of high pressure and temperature and to simulate real environments. It was determined that the microstructural state of steel has a significant effect on the corrosion rate, which increases with increasing volume fraction of pearlite. Understanding the relationship between the microstructural characteristics of steels and corrosion rates can simplify material selection for infrastructure facilities and contribute to more efficient and reliable use of low-alloy carbon steels in carbon capture, use, and storage projects. This study will be useful in selecting favorable microstructures for low-alloy mild steels that can be used for CCUS (Carbon Capture, Use and Storage) infrastructure projects.

The article presents the results of theoretical and experimental studies of manganese reduction processes from oxides of high-quality manganese concentrate obtained by hydrometallurgical enrichment of ferromanganese ores, as well as, from marokite (product of thermal synthesis of concentrate and dolomite) with carbon and silicon. The method of thermodynamic modeling with TERRA software complex determined the optimal temperatures and consumption of reducing agents that ensure the complete reduction of manganese. It was found that any of the above-mentioned reducing agents, or a combination thereof in certain ratios, can be utilized as a reducing agent when using oxide manganese-containing materials for steel treatment. The results of experimental studies made it possible to develop technology for the production of marokite-manganite concentrate and monophase synthetic material (CaMnO₃). They can be obtained using the technology developed by the authors, which includes mechanical and thermal treatment of a mixture of high-quality manganese concentrate and calcined dolomite or lime. Marokite-manganite concentrate is useful for alloying steel with manganese when it is smelted in an electric furnace or in a ladle furnace unit, and a monophasic synthetic material is efficient for the production of metal manganese. Based on the results of thermodynamic calculations and experimental studies, technological parameters for processing steel with marokite-manganite concentrate in an electric furnace and a ladle furnace unit are proposed. Monophasic synthetic material CaMnO₃ should be used as the charge component for the production of metal manganese by the out-of-furnace aluminum thermal treatment, which will increase the thermality of the process, as well as the extraction of manganese at the level of 90 %. The results of experimental studies were obtained using modern research methods with laboratory and analytical equipment, as well as statistical processing methods.

The article presents the results of development of an information modeling system for movement of charge layers and melt accumulation in a blast furnace well. The work is based on mathematical models reflecting modern ideas on the course of physico-chemical phenomena of blast furnace melting and technological features of the blast furnace process. The use of such system makes it possible to determine and visualize the configuration of layers of iron ore materials and coke according to the working space height, taking into account a given ore load in equal-sized annular zones of the blast furnace. In constructing the configuration of the charge layers, when materials are approaching the furnace belly, the peculiarities of their movement are taken into account. This is due to the influence of tuyere zone, primary slag formation processes, and changes in thickness of the coke layer caused by development of the direct reduction process. Calculation of the melt accumulation process in the blast furnace well provides determining the volume of slag remaining there after the notch closure of previous tapping, calculating the dynamics of filling the furnace well with melts of cast iron and slag, determining the volume output of melts of cast iron and slag for the inter-tapping period and calculating the duration of tapping. The developed information modeling system makes it possible to evaluate the dynamics of changes in configuration of layers in the working space height, as well as the process of melt accumulation in the blast furnace well, using really accessible information about a working furnace. The software architecture is described, the characteristics of the modules are presented and its operation is illustrated. The developed system can be used by technological staff of a blast furnace shop to study the processes occurring in blast furnaces, improve the technological modes of operation, predict the melting progress in real time in conditions of operation instability.